As disclosed in Patent Literature 1, there has been a conventionally-known technique to divide the memory to be diagnosed into a plurality of areas, and perform a combination of two types of commonly-known memory diagnoses on a combination of the divided areas to thereby detect a memory fault.
It is common that a diagnosis on a memory applied to a safety device is required to detect two types of faults referred to as “coupling fault” and “stuck-at fault”. The coupling fault is a fault in which the value of a certain cell within the memory causes an unwanted change in the value of another cell. The stuck-at fault is a fault in which the value of a certain cell within the memory is fixed at 0 or 1, and cannot be changed.
The necessary procedure to detect a coupling fault and a stuck-at fault has been disclosed in Non Patent Literature 1.